Lawyers for an SAS sniper are writing to military prosecutors to ask them to reconsider their decision to pursue a retrial on gun charges after he was recommended for discharge from the Army.

Sgt Danny Nightingale is due to face a retrial in July over the alleged illegal possession of a pistol and ammunition after a previous conviction was quashed by Court of Appeal judges.

On Thursday the 38-year-old's lawyer Simon McKay said Sgt Nightingale had been recommended for medical discharge by the Medical Board of the British Army because of serious brain damage caused after a collapse in the Amazon jungle in 2009.

In the light of the recommendation, he has written to the Service Prosecuting Authority to ask if it will re-consider whether it is in the public interest to hold another trial, Mr McKay said.

On Thursday Sgt Nightingale, from Crewe, Cheshire, said he was "devastated" that his SAS service was coming to an end, but recognised the brain damage he suffered in 2009 meant he could no longer carry out his normal duties.

The father-of-two, who on Wednesday pleaded not guilty to the two charges, has argued that the pistol and ammunition were brought back to the UK from Iraq by colleagues, after he had had to return at short notice with the bodies of two fellow soldiers.

On Thursday night a Ministry of Defence spokesman said: "As a matter of course we would never confirm information which is medical in confidence. We do not comment on individual cases.

"In most cases the process that is followed once the medical board has made a recommendation is that the medical board's decision will be considered by the Army Personnel centre in Glasgow before a final decision is taken. Every case is assessed individually. No one who is wounded, injured, or sick will leave the Army until they have reached a point in their recovery where it is right for them to leave."

On Wednesday Judge Advocate Jeff Blackett told Bulford Military Court in Wiltshire there was no abuse of process relating to secret emails concerning the case apparently leaked by a Ministry of Defence source.

Mr McKay told the court the messages - leaked, he said, by an MoD "whistle-blower" - appeared to show the director of service prosecutions consulting the military "chain of command" on whether or not to pursue the case against Sgt Nightingale. But prosecutors said there was nothing "improper" with the conduct alleged in the email.